As a method to prepare (meth)acrylate, for example, a method to react (meth)acrylic acid anhydride with an alcohol is known. In patent literature 1, there is described a method to react (meth)acrylic acid anhydride with a secondary or tertiary alcohol under coexistent of a basic compound having 11 or less of acidity (pKa) in water at 25° C. Purified (meth)acrylic acid anhydride is usually used for production of (meth)acrylates using (meth)acrylic acid anhydride. In patent literature 1, there is described purification methods of (meth)acrylic acid anhydride, neutralizing and washing a reaction liquid containing (meth)acrylic acid anhydride with an alkaline aqueous solution of pH7.5 to 13.5, and in patent literature 2, it is described a method of fractional distillation of a crude product.
However, with the method to neutralize and wash a liquid containing (meth)acrylic acid anhydride, it causes a problem that a part of (meth)acrylic acid anhydride is hydrolyzed, and a large quantity of washing-wastewater is generated. As a result, treatment of the wastewater is necessary. With the method to fractionally distill a liquid containing (meth)acrylic acid anhydride, it causes a problem that a part of (meth)acrylic acid anhydride is contained in a initial distilled product or is remained in a reaction vessel and it can be not recovered, and there exists a risk of generation of polymerization during distillation. As mentioned above, with the method to purify (meth)acrylic acid anhydride, the loss of (meth)acrylic acid anhydride can be not avoided.
In patent literature 3, there is described a process for producing phenyl(meth)acrylate characterized in reacting crude (meth)acrylic acid anhydride with a phenol compound. However, according to examinations of the inventors, it was found that compounds, which is obtained by a reaction of acetic acid or (meth)acrylic acid with at least one side of the double bond in (meth)acrylic acid anhydride by the Michael addition reaction, are contained with several percentage in crude (meth)acrylic acid anhydride. When an alcohol is reacted to the compounds obtained by the Michael addition reaction, it is acknowledged generating the compound having a constitution which is obtained by a reaction of (meth)acrylic acid with the (meth)acrylate represented in the following general formula (II) by the Michael addition reaction. Thus, with the preparation method in patent literature 3, it causes a problem that a yield of the (meth)acrylate under the alcohol standard is deteriorated, and, when the (meth)acrylate which is the objective substance is distilled, it causes a problem that the ester represented in general formula (II) is included.
(In general formula (II), R3 or R4 shows hydrogen or methyl group, and R5 shows an alcohol residue.)
According to examinations of the inventors, it was found that the compound represented in general formula (II) is decomposed into (meth)acrylic acid and a (meth)acrylate at a high temperature. When the (meth)acrylate containing the compound represented in general formula (II) is distilled, (meth)acrylic acid is generated in a late part of distillation at which a distillation liquid temperature becomes high and (meth)acrylic acid is included in the distilled (meth)acrylate, so that purity deteriorates.
When (meth)acrylic acid anhydride and an alcohol are reacted, it may be performed proceeding a method that one of the above component is added with a surplus amount and another component is to be vanished, from the viewpoint of easiness of purification. In addition, when the reaction is not completed, both (meth)acrylic acid anhydride and the alcohol may remain. In particular, when a boiling point of the target product is near to a raw material, namely, when a boiling point of the target product like phenyl methacrylate is near to the boiling point of a feeding alcohol and (meth)acrylic acid anhydride, contents of both raw materials are preferably to be lowered as much as possible.
With the manufacturing method of patent literature 1, (meth)acrylic acid anhydride is dissolved in an alkaline aqueous solution as methacrylic acid transformed by hydrolysis of (meth)acrylic acid anhydride, by using of a surplus amount of (meth)acrylic acid anhydride and by treating of remaining-(meth)acrylic acid anhydride with an alkaline aqueous solution. However, the (meth)acrylate obtained from the alcohol having phenolic hydroxy group is easy to be hydrolyzed, so that the (meth)acrylate is hydrolyzed together when (meth)acrylic acid anhydride is hydrolyzed. As a result, the yield of the (meth)acrylate deteriorates greatly. In addition, (meth)acrylic acid anhydride can be not hydrolyzed efficiently by washing with a weak alkaline aqueous solution such as aqueous solution of sodium carbonate or potassium carbonate. Also, a large quantity of washing-wastewater is generated in these methods.
In patent literature 4, there is described a method to supply a highly reactive alcohol such as methanol and to react the alcohol with remaining-(meth)acrylic acid anhydride. However, an alcohol having methyl ester and phenolic hydroxy group is generated because the (meth)acrylate obtained from an alcohol having phenolic hydroxy group is easy to be transesterificated with methanol. As a result, the yield of the (meth)acrylate deteriorates greatly.